Use the adjective mitigated to describe something that's been made less serious. If your friend gets a serious case of food poisoning, news of her mitigated symptoms will make you feel relieved.
When something has lessened in intensity or seriousness, you can call it mitigated. If a judge decides on a mitigated sentence for your brother the car thief, it means he's not in quite as much trouble as he might have been, and you could say that hosting movie night at your house has mitigated, or reduced, the money you spend at the theater. The Latin root word, mitigatus, means make mild or gentle.